THURSDAY, Feb. 7 (HealthDay News) -- While daily dialysis can boost the overall health of kidney disease patients, it also can put them at higher risk for certain complications, a new study finds.

About 2 million people worldwide receive dialysis treatments. In dialysis, patients use a machine to artificially do what healthy kidneys should: eliminate waste and unwanted water from the blood. Standard dialysis involves three treatments a week, while frequent dialysis involves treatment once each day.

Of course, frequent dialysis requires accessing the blood more often, which typically is done using a long-lasting puncture site through which blood can be removed and returned.

Having the blood cleansed more frequently does typically improve patients' health and quality of life. It wasn't known, however, whether these patients also had any higher risk for complications related to repeated use of the blood-access site.

In this study, researchers led by Dr. Rita Suri, of Western University and Lawson Health Research Institute in London, Canada, conducted two 12-month clinical trials involving 245 patients. The patients were randomly selected to receive either in-center daily dialysis (six days a week) or standard dialysis (three days per week). Another 87 patients received either frequent home-based dialysis or standard dialysis.

In the first hospital-based trial, 31 percent of the 245 patients had to undergo repair of the blood-access site, lost use of the site or were hospitalized due to problems with the site. Complication rates were higher among the frequent-dialysis group: There were 33 repairs and 15 losses in the frequent-dialysis group compared with 17 repairs, 11 losses and one hospitalization in the standard-dialysis group.

Overall, the risk for a problem with the blood-access site was 76 percent higher in the frequent-dialysis group than in the standard-dialysis group, the researchers reported.

Similar trends were seen in the home-based trial, but the results were not statistically significant, according to the study results, which were published online Feb. 7 in the Journal of the American Society of Nephrology.

The findings are the first to show that frequent dialysis may have potentially harmful effects on the blood-access site, and provide valuable information for dialysis patients and their doctors, Suri said in a journal news release.

Two kidney experts said the results are not surprising, since dialysis is always a balancing act between risks and benefits.

"Frequent dialysis has been an area of intense interest since the publication in 2010 of a study from the Frequent Hemodialysis Network (FHN) that found a reduced rate of death and other events with frequent dialysis," said Dr. Steven Fishbane, director of clinical research in the department of medicine at North Shore-LIJ Health System in Great Neck, N.Y.

But he said the new study is a reminder that there is a downside in terms of complications. "Further work will be necessary to determine how to reduce these complications given the important improvement in patient health with frequent dialysis," he said.

Dr. Brian Radbill is associate professor of medicine in the department of nephrology at the Icahn School of Medicine at Mount Sinai, in New York City. He was also involved in the FHN trial that helped confirm the benefits of daily dialysis. Radbill said it was "not surprising" that daily treatments also increased patients' risk for complications.

The needles used to gain access to the bloodstream are relatively large and frequent use raises the odds of complications such as clots and aneurysms, Radbill said. In turn, those complications may lead to burdensome surgeries or loss of the blood-access site altogether.

Still, despite these risks, large clinical trials have "suggested an improvement in self-reported health-related quality of life in those patients who underwent more frequent [dialysis] as compared to those on conventional dialysis," Radbill said. That means that any risks, "must be weighed against the potential benefit of a better quality of life."